An EV tariff (a specific electricity tariff designed for overnight EV charging) is the single most cost-effective optimisation an EV driver can make. The right tariff turns a 60p/kWh public-rapid bill into a 7p/kWh overnight one — roughly a 90% saving. As of May 2026 the market is tighter than ever, with Octopus, EDF, OVO, British Gas, and E.ON all competing on rate, charging window, and integration. Here's how they stack up — and what changes by July or this whole article will be out of date.
Why an EV tariff matters
Standard variable electricity in May 2026 is around 27-29p/kWh on a default Ofgem cap. An EV charging 30 miles per day at around 4 miles/kWh uses about 7.5 kWh — call it 8 kWh with charging losses. On standard rate that's around £2.30/day. On a 7p off-peak tariff: 56p/day. Across 12,000 miles/year, that's roughly £640 saved annually just by switching tariff. The home charger pays for itself in 2-3 years on the tariff differential alone.
The four main contenders (May 2026 rates)
| Tariff | Off-peak rate | Window | Notable |
|---|---|---|---|
| Intelligent Octopus Go | around 7p/kWh | 23:00 - 05:30 (smart charge anywhere in this window) | Native Ohme/Zappi/Wallbox integration; cheapest with smart charger |
| Octopus Go (standard) | around 9p/kWh | 00:30 - 04:30 (fixed) | Older variant, no smart charger needed |
| EDF GoElectric | around 7p/kWh | 23:00 - 06:00 | Wider 7-hour off-peak window |
| OVO Charge Anytime | around 7p/kWh | Smart, plan-based | Pay-as-you-go style; differs from cheap-window model |
| British Gas EV Power | around 8p/kWh | 00:00 - 05:00 (fixed) | Simple, whole-home benefit |
| E.ON Next Drive | around 7p/kWh | 00:00 - 07:00 | Long 7-hour window |
Rates as observed in May 2026 — they move quarterly. Always check the supplier's current rate at signup; the numbers above are indicative, not contractual.
How to choose
If you have an Ohme, Zappi, or Wallbox charger and an EV with API support
Intelligent Octopus Go. The tariff talks directly to your charger and your car to charge in the cheapest 30-minute slots between 23:00 and 05:30. Sometimes you get bonus slots in the daytime if there's surplus renewable on the grid. For most EV drivers with a smart charger, this is the lowest-cost option in the UK in 2026.
If you have a "dumb" charger (or Tesla Wall Connector)
EDF GoElectric or E.ON Next Drive. Both give you a wide off-peak window (7 hours) so you don't need the charger to "decide" when to charge — just set a timer or rely on the car's schedule. EDF is well-established; E.ON sometimes undercuts on rate.
If you charge unpredictably
OVO Charge Anytime. The pay-as-you-go style means OVO works with your charger to find the cheapest moments throughout the day, not just at night. Good for people whose driving patterns vary (e.g. some night-shift workers).
If you have solar PV
Combine Intelligent Octopus Go (overnight cheap) with solar diversion via Zappi (free midday top-ups when sunny). Octopus also has a separate Octopus Flux tariff with high export rates for battery owners — relevant if you have home battery storage alongside solar. See our solar diversion piece.
If you have an EV but also high daytime use (heat pump, work from home)
Consider EDF GoElectric or E.ON Next Drive — their wider off-peak windows give you more flexibility to shift dishwasher/washing-machine/heat-pump load to cheap hours.
The "peak rate" trap
EV tariffs subsidise off-peak with slightly higher daytime rates. On Intelligent Octopus Go, peak rate (May 2026) is around 28-29p/kWh — only marginally above default. But if you use a lot of electricity during the day (heat pump in cold months, electric oven running for hours), the peak premium can erode your savings. Run the maths on your annual kWh split before switching.
How smart EV tariffs actually work
The mechanism behind Intelligent Octopus Go (and similar smart tariffs):
- You tell the app/charger your daily mileage target and "ready by" time
- The tariff system calculates the kWh needed
- It schedules charging across the cheapest 30-minute slots in the off-peak window
- If grid conditions are favourable (high renewable output, low demand), it may add bonus cheap slots outside the standard window
- Your home electricity is billed at off-peak rate during all EV-charging windows automatically
Switching is easy — and Cornwall-friendly
- Confirm you have a smart meter (most Cornwall homes do; if not, your new supplier will install one)
- Choose your tariff via the supplier's website
- Pair your charger to the supplier's app/system (Octopus Mini for non-Intelligent-Go-compatible chargers; native pairing for Ohme/Zappi)
- Switch typically completes in 2-3 weeks
- Cancel anytime — no exit fees on most EV tariffs
What you actually save
Realistic annual savings for a Cornwall household with a 7kW home charger:
- 10,000 miles/year (light driver): around £500 saved vs standard tariff, around £1,800 saved vs public rapid charging
- 15,000 miles/year (average): around £750 saved vs standard tariff, around £2,700 saved vs public rapid
- 25,000 miles/year (heavy driver or PHEV-to-BEV switch): around £1,200 saved vs standard, around £4,500 vs public rapid
The home charger + EV tariff combo recovers its £1,000 install cost in 12-24 months for most drivers.
Want help choosing a charger that works well with Intelligent Octopus Go? Submit your postcode and we'll match you with a vetted Cornwall installer who can recommend a Zappi, Ohme, or Easee based on your tariff plans.
Disclosure
EV Charger Cornwall is a lead generation service. We're not energy switchers; rate comparisons are based on supplier-published 2026 figures and may have changed by the time you read this.